Toxic Effects Of TiO₂ NPs On Zebrafish

With the rapid development of nanotechnology,engineered nanomaterials(ENMs)have been widely used in photoelectricity,biological medicine,cosmetics,and many other fields.ENMs are inevitably discharged into the environment through water,soil and atmosphere during their production,use and disposal processes.The ecological effect of ENMs on the environment has gradually aroused wide attention both at home and abroad.Titanium dioxide nanoparticles(TiO2 NPs)has become a widely used nanomaterial because of its photocatalytic activity and absorption of ultraviolet light of specific wavelengths.This study investigated the toxic effects of rutile TiO2 NPs on zebrafish by its embryos and adults.In the embryo acute toxicity test,exposure to 100 mg/L TiO2 NPs,the hatching rate of zebrafish embryos was not affected,and also did not appear deformity.In the adult toxicity test,studied the effect of TiO2 NPs on oxidative damage in gill,liver,and intestine tissue.Used enzyme linked immunosorbent assay(ELISA)and fluorescence quantitative PCR(Q-PCR)to detect the three antioxidant enzymes:superoxide dismutase(SOD),catalase(CAT)and glutathione S transferase(GSTs),in protein and gene levels.The results showed that under different concentrations of TiO2 NPs,the activities of CAT,SOD and GSTs in gill tissue of zebrafish were lower than those in blank group and conventional TiO2 group.In the 100 mg/L TiO2 NPs exposure group,the activities of CAT,SOD and GSTs were 48.7%,38.2%and 50.3%contrast to control.For liver tissue,just low concentration of TiO2 NPs can reduce the activity of three antioxidant enzymes,and with the increase of TiO2 NPs concentration,the effects were increasing.In the 100 mg/L TiO2 NPs exposure group,the activities of CAT,SOD and GSTs were 32.3%,26.22%and 40.2%compared to control.After exposure for 7 days,in the 100 mg/L TiO2 NPs exposure group,the relative expressions of three genes of cat,sod and gsts in gill tissues of zebrafish were 7.13±0.57,2.34±0.14 and 4.18±0.64,which were 7.1,2.3 and 4.2 times compared to control.In liver tissue,the relative expression of three genes of cat,sod and gsts in the 100 mg/L TiO2 NPs exposure group were 7.77±0.85,3.70±0.37 and 3.27±0.07 respectively.In the 100 mg/L TiO2 NPs exposure group,the relative expression of three genes of cat,sod and gsts in intestinal tissue was 4.75±0.15,1.66±0.09 and 1.50±0.22 respectively,which were 4.8,1.7 and 1.5 times of blank control group respectively.It indicates that zebrafish can increase the expression of antioxidant genes and enhance the expression of antioxidant enzyme in order to resist external adverse stimuli in long-term exposure to high concentration of TiO2 NPs.